1. Field of the Invention
The present invention relates to an image producing apparatus for producing images of road, railroad and other map symbols by using a coordinates input device provided with a pen or a mouse.
2. Description of the Related Art
In these days, wordprocessors are generally used for writing a document. Some documents written by a wordprocessor include not only a letter but an image. There are some wordprocessors which have a coordinates input device provided with a graphical user interface such as a tablet, a digitizer and a mouse. FIG. 9 shows a concept of a wordprocessor with a coordinates input device. It is ordinary to use a pen or a mouse in order to input an image to a document by the wordprocessor, as shown in FIG. 9.
A map is often drawn up by a wordprocessor, because a map is very useful for pointing out a location. Roads, buildings, railroads and other map symbols are often drawn in the map as a mark. Special software for image drawing is generally used for producing the above mentioned map. FIG. 11 shows an example of the map.
In such a wordprocessor with a coordinates input device shown in FIG. 9, it is convenient and useful that a road symbol or a railroad symbol is generated in accordance with a free curved line inputted by the coordinates input device as shown in FIG. 9. However, many conventional software of image drawing have limitations that the forms of roads and railroads must be straight or predetermined arc, because of their difficulties in drawing freehand curved lines with accuracy.
Symbols shown in FIG. 12a and FIG. 13a are generally used as a representation of a railroad in a map. In this specification, the symbol shown in FIG. 12a is called "white and black pattern railroad" and the symbol shown in FIG. 13a is called "+ pattern railroad".
The conventional way of producing "white and black pattern railroad" by using a wordprocessor or a personal computer is as follows.
1. Draw two parallel line as shown in FIG. 12b. PA1 2. Paint black zones in same space as shown in FIG. 12c. PA1 1. Draw a straight line as shown in FIG. 13b. PA1 2. Draw short lines to cross the straight line at a right-angle as shown in FIG. 13c. PA1 1. In a method of producing each two straight lines, it is difficult to draw two parallel lines with accuracy. PA1 2. In a method of producing two parallel lines by moving one line in parallel, the curved line as shown in FIG. 14b is produced by parallel movement of the curved line as shown in FIG. 14a. PA1 3. Lines between white zones and black zones should be drawn at a right-angle to a direction of the "white and black pattern railroad". It is preferable to produce the lines automatically between white zones and black zones and to paint the black zones automatically. However, it is not easy to determine the direction of the line between white zone and black zone at curving portion in a case like FIG. 15. PA1 1. Free curved railroad symbols and road symbols are drawn very easily, because their inputs are made directly through a coordinates input means such as a pen or a mouse. PA1 2. In a case of drawing railroad symbols, "white and black pattern" or "+ pattern railroad" is generated automatically in a pertinent direction in accordance with a judgment from the stored coordinates points. PA1 3. In a case of drawing road symbol, cubic crossed road symbol is easily generated by drawing a continuous line by drawing a first line with a first color and a second line with a second color at the same time. In a case of erasing a cubic crossed portion, the cubic crossed portion is erased by drawing the second line with the second color in accordance with the stored coordinates in the coordinates storing means.
The conventional way of producing "+ pattern railroad" by using a wordprocessor or a personal computer is as follows.
The symbol composed of straight lines, curved lines and arcs is used generally as a representation of a road in a map. In this specification, this symbol is called "round edge road". The conventional way of producing "round edge road" by using a wordprocessor or a personal computer is drawing each of straight lines, curved lines and arcs one by one.
For the conventional way of drawing a railroad, it is easy to draw straight railroad symbols. However, there are some problems in a case where drawing railroad symbols includes free curve.
For producing "white and black pattern railroad", there are some problems as follows.
For producing "+ pattern railroad", it is very troublesome to draw many perpendicular short lines across the drawn center line. It is difficult to determine the direction of the perpendicular short lines at curving portion like such a case of "white and black pattern railroad".
In a conventional method of producing road symbols, it is necessary to draw many straight lines, curved lines and arcs. For example, the road symbols shown in FIG. 16 is composed of eight straight lines, six curve lines and six arcs.
A pair of strait lines must be parallel to each other with accuracy. A pair of curved lines must be parallel to each other with accuracy. In a case where producing straight road symbols, it is possible to produce by parallel movement same as above mentioned case of producing railroad symbols. However, it is difficult to produce curved road symbols as shown in FIG. 14a in the same way.